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[Scott Charbobs]

Could someone explain in laymans terms what does SPL do, and is it something I need to look at when comparing speakers?  Thanks in advance

[Adam Whetham]

Scott Charbobs wrote on Fri, 19 February 2010 15:38

Could someone explain in laymans terms what does SPL do, and is it something I need to look at when comparing speakers?  Thanks in advance

SPL does nothing. its a unit of measure.

SPL= Sound Pressure Level

[Tony "T" Tissot]

Get this: http://www.amazon.com/Live-Sound-Reinforcement-Mix-Audio/dp/ 0918371074

or the Yamaha one -


Good first step.

[Art Welter]

Scott Charbobs wrote on Fri, 19 February 2010 14:38

Could someone explain in laymans terms what does SPL do, and is it something I need to look at when comparing speakers?  Thanks in advance

Sound Pressure Level, as Adam says, is a unit of measure, using decibels, dB SPL.

It can be an average of all frequencies, (flat weighting) or  various weightings like A or C.

A 3 dB increase in speaker SPL requires double the power, a 6 dB increase, four times the power, a 10 dB increase, ten times the power.

A 10 dB increase will only sound about twice as loud.

Assuming a speaker can handle the power (and does not power compress), going from 1 watt to 10 watts to 100 to 1000 will each result in a 10 dB change, for a theoretical 127 dB output from a speaker that has a sensitivity of 97 dB one watt one meter.

A speaker that is three dB more efficient would only require 500 watts to do the same.

The frequency response must be considered in the comparison, of course.

Art Welter

[Don Boomer]

Which is not exactly the same thing as "loudness"

[Brad Weber]

Art Welter wrote on Fri, 19 February 2010 17:00

Sound Pressure Level, as Adam says, is a unit of measure, using decibels, dB SPL.

SPL by itself is simply Sound Pressure Level, a RMS pressure level usually identified in Pascals (Pa) but that could also be in N/m**2 or PSI or other units.  No dB involved.

The dB(SPL) is a method devised to present sound pressure levels in a perhaps more usable fashion.  dB(SPL) is 20log(RMS sound pressure level/a reference sound pressure level) and for sound in air a reference value of 20 micropascals (2x10**-5 Pa) is used.

[Paul O'Brien]

Scott Charbobs wrote on Fri, 19 February 2010 16:38

and is it something I need to look at when comparing speakers?

Yes absolutely.. matter of fact it's probably more important than the speakers rated power handling capacity.. a number everybody seems to be drawn to and something marketing types all too often over-advertise and exagerate. Ideally you want  speakers that produce high output(SPL) levels with little input power, but be prepared to do some digging to get real numbers on this. In sales media you will often only see calculated maximum or peak output levels and somtimes the numbers only represent one test frequency, when what you really want to see are actual measured long term output levels over the whole speaker bandwidth. And incredible as it sounds sometimes the published specs are from frequencies outside the typical operating range of the speaker system.. like a sub that is rated for 109db@1w at 1khz. You will see this more often with subwoofers and from "lowend" brands so keep an eye out for it. The old adage still applies.. if it sounds too good to be true it probably is.